The aim of the present work is to experimentally investigate the combined effects of compression ratio, nozzle opening pressure and injection timing on the performance and emissions of a CI (compression ignition) engine operated with an emulsion fuel obtained from CB (carbon black). The emulsion contained CB 10%, 2% water, 85% diesel and 3% surfactant was denoted as CBWD10. Tests were carried out with the CBWD10 emulsion in a single-cylinder, four -stroke, air cooled, DI (direct injection) diesel engine developing power of 4.4 kW at a constant speed of 1500 rpm. The experimental results were obtained for the performance and emission parameters of the emulsion fuelled engine when the engine was subjected to different injection timing, nozzle opening pressures and compression ratios. With respect to the original compression ratio of the engine which was 17.5, one lower (16.5) and one higher compression ratio (18.5) were used in the investigation. Similarly, injection timing was advanced to a maximum of 3 CA, and the nozzle opening pressure was set at 200,220 and 240 bar at a regular interval of 20 bar. The results were analysed and compared with those of the normal diesel engine operation and presented in this paper. (C) 2015 Elsevier Ltd. All rights reserved.